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Strep A is a dangerous bacterium. It causes sore throats which, although unpleasant for the sufferer, are not usually dangerous and get better without treatment.
Children often progress to scarlet fever, which can be more dangerous; in some people, it progresses to an invasive form of the disease called iGAS (invasive Group A Strep), which can be thought of as a nasty pneumonia or septicaemia.
There is no difference in the strains causing sore throat, scarlet fever and iGAS; progression depends on the individual. We don’t know how many strep throat infections there are, because the diagnosis is complicated by viral sore throats. Many with infections will not see their GP or pharmacist.
Scarlet fever and iGAS, on the other hand, are reportable conditions. We have year on year data. We know the mix of strains present. We also know the number of deaths in children, although they are not routinely reported. The majority of deaths are in adults. Mortality in the over 75s is 20 per cent.
Strep A is very transmissible. A limited number of published papers show this in adults with sore throats, but we know that scarlet fever and iGAS are usually recognised in outbreaks which will close a school or devastate a care home.
Strep A sore throats remain infectious for at least 14 days. People with strep A are non-infectious within 24 hours of starting treatment. So, if you have scarlet fever, you get antibiotics and can return to school or work 24 hours after your temperature has settled. But if you have strep A sore throat, you go to school or work and spread it around.
The UK Health Security Agency (UKHSA) writes the guidance for scarlet fever and iGAS. They aim to control outbreaks and advise GPs to be particularly vigilant when there are high recorded incidences. The guidance for sore throats is written by NICE (the National Institute for Health and Care Excellence), whose whole ethos seems to be to play down the situation.
“Two years ago, we should have been leading the way. Instead, we continue to ignore a very important report”
NICE guidance rightly says that most sore throats are likely to be viral and get better on their own. We know people treated with antibiotics get better a couple of days earlier at most. NICE recommends the use of a clinical scoring system and antibiotics for people with the most severe sore throats, which has several initial flaws:
- The issue of transmission was considered ‘out of scope’
- The incidence of reported scarlet fever (and associated deaths in children) and iGAS were increasing
- NICE recommended the use of clinical scoring systems that are not very accurate
- NICE recommended against the use of point-of-care diagnostics (POCT).
The guideline does not take into account transmission and does not consider the incidence of the more dangerous elements of infection. The clinical scoring systems are based on the likelihood that the more severe sore throats are likely to be strep A, so lower grade strep A infections can be missed and a proportion of people with bad viral sore throats receive antibiotics they don’t need.
A 2016 report into antimicrobial resistance commissioned by David Cameron states: “[High income countries] should make it mandatory that by 2020 the prescription of antibiotics will need to be informed by data and testing technology wherever it is available and effective in informing the judgement to prescribe. Governments, regulators and health system leaders should consider incentives to facilitate the uptake and use of rapid point-of-care diagnostics in primary and secondary care.”
Two years ago, we should have been leading the way. Instead, we continue to ignore a very important report.
NICE does not recommend POCT, not because of concerns over their ability to detect infection – sensitivity 96 per cent, specificity 98 per cent. They looked at a study comparing the clinical scoring system to a rapid POCT, which concluded that the same number of prescriptions for antibiotics were issued. In other words, POCT does not reduce antibiotic prescribing. But the patients that received antibiotics were different in the two study arms, so you might conclude that POCT ensured the right people got antibiotics.
NICE also recommends the use of delayed antibiotics when the clinical scoring system gives a middle result. How can you possibly recommend delayed prescriptions for people that might have a very transmissible disease?
Commissioning bodies in England have put pressure on GPs not to prescribe antibiotics for sore throats. While downward pressure on inappropriate antibiotic prescribing is important, this could have been done in association with POCT. Unfortunately, even if a GP wanted to use POCT, there is no reimbursement method in their contract, so they would have to foot the bill and run the insurance risk.
My conclusion is simple. NICE guidance on sore throat has led to an underdiagnosis and undertreatment of strep A infections in the throat. This has led to the increase in community reservoir and the increase in scarlet fever and iGAS over time. It’s a predictable disaster.
Mark Robinson is a director of Connect2Pharma, who supply an OSOM strep A test for point-of-care testing.
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